Catalytic oxidation of aromatic hydrocarbons in presence of nitroalkanes



Patented Mar. 21, 1950 CATALYTIC OXIDATION OF AROMATIC HY- DROCARBONS INPRESENCE OF NITRO- ALKANES Herman Pines and Bruno to Universal OilProducts Comllls assignors Kvetlnskas, Chicago,

pan'y, Chicago, 111., a corporation of Delaware no Drawing. ApplicationJune 26, 1946,

= Serial No. 679,574

9 Claims. ll

This invention relates to a process for oxidizing aromatic hydrocarbonsand particularly b enzene hydrocarbons.

An object of this invention is to produce aromatic alcohols andaromaticcarbonyl compounds.

Another object of this invention is to oxidize an aromatic hydrocarbonin the presence of a nitrated aliphatic hydrocarbon.

Still another object of this invention is to oxidize an aromatichydrocarbon by means of an oxygen-containing gas in the presence of anitroalkane.

A further object of this invention is to oxidize an alkyl benzenehydrocarbon in the presence of a catalytic amount of a nitroalkane.

A still further object of this invention is to oxidize an aromatichydrocarbon in the presence of a catalyst comprising a metal selectedfrom the group consisting of the metals having atomic numbers of from 23to 30, inclusive, and in the presence of a nitroalkane.

One specific embodiment of the present invention relates to a processfor oxidizing an aromatic hydrocarbon which comprises reacting saidarematic hydrocarbon and an oxygen-containing gas in the presence of anitroalkane.

A further embodiment of this invention relates to a process foroxidizing an aromatic hydrocarbon which comprises reacting said aromatichydrocarbons and an oxygen-containing gas in the presence of anitroalkane in a reaction zone containing a metal selected from thegroup consisting of the metals having atomic numbers of from 23 to 30,inclusive.

still further embodiment of this invention relates to a process foroxidizing an alkyl benzene hydrocarbon which comprises reacting saidbenzene hydrocarbon, a nitroalkane, and an oxygen-containing gas in areaction zone containing a refractory packing material composited with ametal selected from the group of metals having atomicnumbers of 23 to30, inclusive."

We have found that aromatic hydrocarbons and particularly aromatichydrocarbons of the benzene series are oxidized readily by anoxygencontaining gas in a reaction zone containing a refractory packingmaterial upon which a small amount of a metal or a metal oxide isdeposited. The oxidation process is also catalyzed by 2. nitroparafdnwhich may be mixed with the aromatic hydrocarbon charged to the processor it may be introduced to the reaction zone by other means.

Aromatic l'lydrocarbons such as toluene, xylene, ethyl benzene, cumene,cymene, a butyl benzene,

Lil

and other allrylated benzenes, naphthalene, an 55 alkylated naphthalene,and other polynuclear and alkylated polynuclear aromatic hydrocarbonswhich are oxidized by our process have at least 7 carbon atoms permolecule and include alkyl benzene hydrocarbons and polycyclic aromatichydrocarbons.

Our process is carried out in the presence of a liquid catalyst, a solidcatalyst, and preferably in the presence of both a liquid catalyst and asolid catalyst, the latter employed as a reactor packing material.

Liquid catalysts which we employ comprise nitroaliphatic hydrocarbonsand particularly the nitroalkanes which are also referred to as thenitroparafiins. The following table gives the boiling points andspecific gravity of some of the nitroparaflins used in our process,although other nitroparafiins containing more than four carbon atoms permolecule, and particularly the nitropentanes are also useful asoxidation catalysts.

- Specific Compound fg fla giiogig Nitromethane 101 1.139 Nitroethane114 1. 052 l-Nitropropane 132 l. 003 2-Nitropropane 120 0.992l-Nitrobutane 151 0. 975

The solid catalysts which we use in our process as packing material inthe oxidation reactor comprise metals with atomic numbers of 23 to 30,inelusive, thus including the metals vanadium, chromium, manganese,iron, cobalt, copper, and zinc, supported by a refractory packingmaterial such as crushed firebrick, granular pumice, quartz chips,crushed porcelain. silica, or other refractory granular materials whichdo not have a harmful influence upon the oxidation reaction.

Such composites of a refractory packing material and a metal areproduced preferably by dissolving a metal salt of an organic acid andparticularly a metal salt of a long chain fatty acid, such as a metalstearate, in a normally liquid aromatic hydrocarbon which is oxidized byour process. Thus from about 0.1 to about 0.5% by weight of metal saltis dissolved in a normally liquid aromatic hydrocarbon and the resultantsolution is then conducted to a heated reaction zone containing arefractory packing material in granular form or small particles. Oxygen,air, or another oxygen-containing gas is charged simul taneously to thereaction zone containing the packing material in order to efiectoxidation of the aromatic hydrocarbon. During this oxidation 3treatment, the metal salt of the organic acid which is dissolved in thearomatic hydrocarbon and charged to the reaction zone is decomposedtherein and the resultant metal oxide is deposited upon the refractorypacking material to form a highly active oxidation catalyst. The metalsalt, which is sometimes referred to as a metal soap, is thus introducedeither continuously or intermittently as clesiredin order to maintain inthe reaction zone an amount of metal oxide suflicient to catalyze theoxidation of the aromatic hydrocarbon charged thereto together with theaforementioned liquid catalyst comprising a nitropar afi'iln or amixture of nitroparaflin.

Our oxidation process may be carried out in either a batch operation ora continuous type of operation, although the latter is generallypreierred. The oxidation treatment is efiected at a temperature of fromabout 50 to about 200 C. and at a pressure of from substantiallyatmospheric to about 100 atmospheres. The oxidizing medium employedcomprises air, oxygen, a mixture of air and oxygen, or either air oroxygen diluted with an inert gas.

The nitroalkanes which are the liquid catalysts preferred in our processmay be substituted or partially substituted by an oxide of nitrogen,particularly nitrogen dioxide, nitrogen trioxide, and nitrogentetraoxide.

The following examples are given to illustrate the results obtained inthis process, although the data presented are not introduced with theintention of restricting unduly the broad scope of the invention.

Example I Cumene containing 0.5 mole per cent of a nitropentane and airwere charged simultaneously to a steel reactor, containing granularpumice supporting 0.9% by weight of manganese oxide and maintained at atemperature of 150 C. and operating at a pressure of 35 atmospheres. Themixture of cumene and nitropentane was charged at a rate correspondingto an hourly liquid space velocity of 1.6 and the amount of airintroduced to the reaction zone was such that the molar ratio of oxygento hydrocarbon in the. reaction mixture was 3. By this treatment, 39mole per cent of the cumene was oxidized per pass and on a recycle basisyielded 56 mole per cent of acetophenone and 21 per cent ofdimethylphenylcarbinol.

Example I! In another run, cumene was mixed with 2 mole per cent ofnitromethane and the iesultant solution was subjected to the oxidationtreatment as described in Example I. Twenty-nine per cent of the cumenewas converted per pass with the formation on a recycle basis 01' 45 percent of acetophenone and 30 per cent of dimethylphenylcarbinol.

The nature of the present invention and its utility are evident from thespecification and examples, although neither section is introduced tolimit unduly the generally broad scope of the invention.

We claim as our invention:

1. A process foroxidizing an aromatic hydrocarbon of at least '7 carbonatoms per molecule which comprises reacting said hydrocarbon with anoxygen-containing gas in the presence of a nitroalkane.

2. A process tor oxidizing an aromatic hydrocarbon of at least 7 carbonatoms per molecule which comprises reacting said hydrocarbon with anoxygen-containing gas in the presence of a nitroalkane and an oxide of ametal having an atomic number of from 23 to 30, inclusive.

3. A process for oxidizing an aromatic hydrocarbon of at least '7 carbonatoms per molecule which comprises reacting said hydrocarbon with anoxygen-containing gas in the presence 01! a nitroalkane at 'atemperature of from about 50 C. to about 200 C.

4. A process for oxidizing an aromatic hydrocarbon of at least 7 carbonatoms per molecule which comprises reacting said hydrocarbon with anoxygen-containing gas at a temperature of from about 50 C. to about 200C. in the presence of a nitroalkane and an oxide of a metal having anatomic number of from 23 to 30, inclusive.

5. The process as defined in claim 1 further characterized in that saidhydrocarbon is an alkyl benzene.

6. The process as defined in claim 2 further characterized in that saidhydrocarbon is an alkyl benzene.

'1. The process as defined in claim 1 further characterized in that saidhydrocarbon comprises cumene.

8. The process as defined in claim 2 further characterized in that saidhydrocarbon comprises cumene.

9. A process for producing dimethylphenylcarbinol and acetophenone whichcomprises reacting cumene and air in the presence of nitromethane at atemperature of from about 50 to about 200 C. and at a pressure of fromabout 1 to about atmospheres in a reaction zone containing a granularcomposite of manganese oxide and pumice.

BRUNO KVETINSKAS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,813,606 Binapfl et al July 7,1931 2,245,528 Loder June 10, 1941 2,376,674 Emerson et a1. May 22, 1945OTHER REFERENCES Gimmelman et al., Acta Physicochim. URSS., vol. 7,pages 221-246 (1937).

Gimmelman et al., Chemical Abstracts, vol. 31, column 8287 (1937).

Ajello et al., Chemical Abstracts, vol. 33, 4581- 4582 (1939).

Berezovskaya et al., Chemical Abstracts, vol. 39. 2024 (1945).

1. A PROCESS FOR OXIDIZING AN AROMATIC HYDROCARBON OF AT LEAST 7 CARBONATOMS PER MOLECULE WHICH COMPRISES REACTING SAID HYDROCARBON WITH ANOXYGEN-CONTAINING GAS IN THE PRESENCE OF A NITROALKANE.